1. Field of the Invention
The invention relates to electric connectors to be surface-mounted on a wiring board. In particular, the invention is directed to an electric connector having a predetermined number of contact fittings, each being bent so as to be substantially 7-shaped or inverted U-shaped and being designed to be brought into contact with a flexible printed card (FPC) that is inserted into the electric connector.
2. Related Art
An exemplary conventional electric connector for FPCs of this type is shown in FIGS. 3 A, B and C and FIG. 4 (A). This electric connector 5 has a predetermined number of contact fittings 60 and a main body portion 50. Each contact fitting is bent so as to be substantially 7-shaped or inverted U-shaped. The main body portion 50 has a predetermined number of slitlike insertion portions 52 juxtaposed along the length so as to confront each other across the width. Each contact fitting 60 is inserted into the corresponding slitlike insertion portion 52.
Each contact fitting 60 is constructed of a contact piece portion 62, a straight portion 64, and a bent terminal portion 66. The contact piece portion 62 is substantially obtuse-angled so that the contact piece portion 62 is brought into contact with each of terminal portions 72 formed on both surfaces of an FPC 70 such as shown in FIG. 4 (B) which is inserted into the main body portion 50 from an upper opening 53. The straight portion 64 is formed continuously from the contact piece portion 62. The bent terminal portion 66 is about 90.degree. bent from the straight portion 64 in a direction opposite to the contact piece portion 62. The bent terminal portion 66 is designed to be surface-mounted. As shown in FIG. 6, a press-in protuberance 67 is formed in the vicinity of the middle of the straight portion 64. The press-in protuberance 67 is designed to bite into the corresponding insertion portion 52 while projecting in the widthwise direction of the contact fitting from the contact piece portion 62 and the bent terminal portion 66.
The thus constructed contact fittings 60 are inserted into the corresponding insertion portions 52 of the main body portion 50 by squeezing each contact fitting 60 whose terminal portion 66 is not yet bent as shown in FIG. 6 from below the corresponding insertion portion 52 with the contact piece portion 62 thereof facing inward (toward the center). As a result, the press-in protuberance 67 is fixed by biting into the inner side surface of the insertion portion 52. Hence, the lower part of the contact piece portion 62 is brought into pressure contact with a central partition wall 55 of the main body portion 50 by the resiliency thereof.
Then, by bending the terminal portion 66 about 90.degree. in the direction opposite to the contact piece portion 62, the bent terminal portion 66 becomes coplanar with the lower surface of the main body portion 50. As a result, when the electric connector 5 is placed on a wiring board 40, the bent terminal portion 66 comes in contact with the wiring pattern, and the bent terminal portion 66 and the wiring pattern are connected and fixed by soldering.
In the aforementioned conventional electric connector 5, a clearance, although very slight, is produced between the bent terminal portion 66 of the contact fitting 60 and the corresponding insertion portion 52. This is shown in FIG. 5 (partial bottom view) where the contact fittings 60 are inserted into the slitlike insertion portions 52.
The presence of such clearance causes two adjacent bent terminal portions 66 to move along the length of the electric connector and therefore makes a distance .alpha. between the two adjacent bent terminal portions 66 variable, and this in turn moves the bent terminal portions 66 out of position corresponding to the wiring pattern of the wiring board 40 on which the electric connector is placed. As a result, the soldering area is reduced, thereby impairing the strength of soldering against the separation of soldered parts.
Further, in the aforementioned conventional electric connector 5 for FPCs, it is required that the terminal portion 66 be bent about 90.degree. in the direction opposite to the contact piece portion 62 after the contact fitting 60 has been squeezed into the corresponding insertion portion 52 of the main body portion 50. However, when the terminal portion 66 is bent in this way, the straight portion 64 (particularly) the upper part thereof, and the contact piece portion 62 moves toward the middle as shown by the one dot chain line in FIG. 4 (A). As a result, it is likely that the FPC 70 will not be inserted or that the contact fittings 60 will not come in good contact with the FPC 70.